Confirmed, on both counts. The good news is that I bought the brake booster connector seal a while back expecting it to have failed. I'll need to get two outlet duct seals, part number AJ86892, replace all of it and see where I'm at...

 

No Ken, quite the opposite. I think your fixing the seals will fix the cat efficiency problems. Your MAF and MAP are saying the engine is running unhappy and the o2's are saying the engine is lean causing the trims to max out which will hurt your cats if left unchecked. Downstream o2 aren't happy because they are reading too rich and it's coding on that vs. an engine efficiency problem because OBDii cares about emissions more than performance. If you squint your eyes and think about it, it could make sense.

At any rate carry on and post up some pics because I'm sure I'll be following down this road this winter on my XKR.

 

As a quick experiment, I tore a strip of duct tape in half lengthwise, fished it under the bank 2 outlet duct seal, pulled it tight and sealed it on itself, then repeated with the other half. My drive in to work this morning was pretty nice. Essentially zero engine stumbles, STFT and LTFT added together was always less than 10%, and my fuel economy went up.

It's interesting watching the LTFT relearn. As I sat at stoplights, idling, the trim levels - which had been firewalled at +19.5%, started creeping down slowly. As they came down, STFT crept up (from very negative to offset the big positive LTFT). I studied industrial control logic, feedback, hysteresis, damping and all that in college. Never really used it (except for a few "clever" robotics projects), but it's cool watching it all work together in the car...

Ken

 

Did you run into any seized bolts in your Jag? Mine was a pain when I threw in new cats. Finally got new studs, because people tend to break them when you think your loosening the bolt. Nail those issues bro it's hella worth it running smooth again.

 

I think the current working theory is that my vacuum leaks are causing the cat/O2 codes as a red herring. I won't replace the cats if I don't have to. I may, some time later this summer - or if I get more codes related to them - do a backpressure test using the O2 sensor bung hole.

However, to directly address your question, I've run across plenty of seized bolts on exhaust systems before. PB Blaster + torch is generally the magic to getting those unstuck. The last time I did exhaust work was on a Suburban. I didn't even bother taking a wrench to those nuts (exhaust manifold is mounted on studs). First, I soaked them with PB Blaster and let them sit overnight. Next day, sprayed more and took a torch after them. They came off easy

Ken

 

Hi Ken,

I would not use the car too much with those fuel trim readings because you will be damaging the cats. These are quite expensive.

 

Exhaust wasn't that bad. Put the car on decent stands, spray the connections and bolts. Then run it until the just starts to evaporate. Shut it off, spray it again and loosen while hot. I mangled one of the resonance straps on a cat when a bolt refused to come apart. Took a couple applications of heat and juice before everything came apart. That part is in by rebuild thread if you want pics.

 

"I already have the stupid brake booster hose seal kit, so there's that."

the repair would be better modified as:



https://www.jaguarforums.com/forum/x...ng-fix-105997/

 

I would use the brass fitting as it's a MUCH better repair. Mine has been perfect since I replaced it 15K miles ago.

That was the post I found and followed to fix my 2005 STR.
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I hear you, but that requires me to pull the throttle body. Isn't that, like, a HUGE effort? The push-fitting seems like I can do it in-situ. Maybe?

 

You could try it. You have lost nothing if it does not work, then you go the other way.

 

You will never get the factory fitting out and replaced while it's on the car.

Yes the SC inlet elbow needs to be removed to do the repair. You need to knock the factory brass fitting out from the inside of the elbow.
Note the plumbing brass fitting will cut new threads when screwed in so no need to thread or enlarge the factory hole.

Sorry!
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Well, I replaced the SC outlet duct seals. Re-smoked afterward, and it looks like the last one is the brake booster hose to the TB. I dabbed a little JB weld on the hose-brass fitting junction after cleaning it with carb cleaner, then electronic parts cleaner. It's a hack, but it'll do until I can find a day to tear it all out and do it proper.

At least my fuel trims are within reason again Next thing on the agenda is actually a transmission drain and fill - a first for me with this car...

 

I think you are making good progress!

Get to the P/B fitting when you can. You know what to do if it starts leaking again. And it will!!
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Ditto. Also Yamaha makes an interesting sealant called Yamabond. It's kind of a goopy rubber / urethane glue / gasket maker. It's pretty good for random suction leaks because it'll suck into the gap and if it's not too wide it'll seal it up. It's meant for rebuilding outboard motors.